The orthodontic clamps or brackets are used in orthodontics in tooth-alignment correction devices. A bracket is an element aimed at being fixed through gluing to the front face, and sometimes to the back face, of each tooth, in order to serve as a clamp for an arch. This arch is usually rigid or shape memorizing, made out of metal. This arch is fixed to each bracket, generally at the level of a groove provided for in the latter. The cross-section of this arch can be designed round, square or rectangular.
The problem experienced with such a device resides in maintaining the arch in the groove of each bracket so as to prevent it from being released from it. The devices of the state of the art comprise various means for maintaining the arch in place in said groove.
One device contemplates maintaining the arch by placing a metal binding, in the form of a metal wire, or made out of synthetic material, in the form of a rubber band, on the bracket, through securing tabs. These securing tabs are made on both sides of said groove and on the outer walls of said bracket, arranged on the occlusal and gingival sides of the bracket, so that the binding is fixed to it to close the groove and to block the arch in the latter. However, a drawback resides in that the binding can be released, in particular when brushing the teeth, and may eventually damage the gum in the case of the metal wire, or may even be swallowed. Moreover, the metal wire is twisted and bent at its ends, thus being able to nip or irritate the mucosa through friction in the event it suddenly moves. The rubber bands lose their quality quickly and become dirty depending on the saliva and on the food habits, resulting into an even less aesthetic aspect of the bracket, and it is thus necessary to change them regularly. Finally, a metal or elastic binding requires a placing and replacing technique and time.
In order to cope with these drawbacks, some devices are provided with mechanical means for automatically locking the groove. These automatic locking means comprise a removable part aimed at co-operating with the bracket. This part can be in the form of a hinge articulated on said bracket or of a member coupled through snapping on or the like.
A device comprising a removable part articulated through a hinge has the drawback of being complex as regards the manufacture of the bracket. Moreover, the hinge is fitted on an axis or a pivot likely to be released or even to break.
A known snap-on locking device comprises a bracket the base of which aimed at being glued to the tooth is fixed to an upper portion in which the groove aimed at receiving the arch is provided for. On the side walls of the groove and on both sides of the latter are provided for one or two side grooves aimed at receiving a removable member, the member covering the upper opening of said groove being aimed at blocking the arch in the latter. In particular, according to a particular embodiment, the removable member is in the form of a metal arch having elastic characteristics so that it is deformed during its installation and that it recovers its original shape in locked position, the longitudinal edges of the member co-operating with the side walls of the groove.
Moreover, securing tabs remain present in order to add an elastic or metal binding, if necessary.
Even though this type of device does not use an elastic or metal binding, it has however the drawback of having a removable member having the above-mentioned drawbacks, in particular, it is likely to be released.
Moreover, a removable or articulated member has a backlash that can gradually increase. Finally, the shape of a bracket supporting a removable or articulated member is complex, thus increasing its design and its manufacturing cost.